EP0318398A1 - Diltiazem sustained release form and medicament thereof - Google Patents

Abstract

Microgranules containing a core coated with layers containing diltiazem and an outer membrane. This membrane consists of a mixture of shellac and ethylcellulose, or a mixture of ethylcellulose with a plasticiser. <??>The retard form obtained by the process of the invention enables the number of daily doses to be decreased, lower concentration peaks to be produced in the hours following ingestion and a concentration which remains higher over time to be obtained.

Description

The present invention relates to a new dosage form of Diltiazem hydrochloride (hereinafter referred to more simply as Diltiazem), and to its process of preparation.

This body has the formula:

It is in the form of a powder or white crystals, odorless, having a melting point between 208 and 212 ° C. Diltiazem is known as an inhibitor of calcium influx through the specific membrane channels of a variety of cells. By this mechanism, it exerts a depressant effect on the cardiac pacemaker activity and on the atrioventricular nodal conduction resulting in a negative chronotropic effect. Diltiazem seems to have a weak negative inotropic effect on the heart muscle and causes vasodilation of the smooth muscles. Diltiazem reduces intracellular sodium by stimulating the sodium-potassium pump of smooth muscles and other types of cells. This effect is responsible membrane stabilizing effects and diuretic (non-vascular) action on the renal tubules. Clinically, Diltiazem is mainly used as an antianginal agent, as well in chronic stable angina as in unstable angina. It also has activity in arrhythmias and can be used in other cardiovascular conditions such as congestive heart failure and Raynaud's syndrome, as well as in cerebral and peripheral circulatory failure.

However, Diltiazem is currently widely studied in hypertension, an indication already recognized by the authorities of many countries.

It is a product that has few side effects, especially when compared to other calcium antagonists such as Nifedipine or Verapamil, and is therefore possible in long-term treatments.

Diltiazem is currently used in the form of immediate-release tablets, dosed at 30, 60 and 90 mm. The dosage is 180 mg divided into two or three doses and, in severe cases 240 mg, even 360 mg, per day.

The literature review shows that Diltiazem has a very rapid absorption and that the concentration peak is reached between three and a quarter to four hours. The half-life is four to seven hours. There is no saturation phenomenon observed at therapeutic doses and, after repeated administration, therefore, there is no accumulation of the drug. The tolerance of Diltiazem is very good. Significant variability has been observed between the pharmacokinetic parameters of the subjects, which makes it difficult to maintain plasma concentrations in the therapeutic window. These various data and the experience acquired during the development of numerous products have prompted the applicant to try to optimize the already existing dosage form of Diltiazem by choosing a form a prolonged release presented in capsules, tablets or sachets containing microgranules.

The prolonged release form should reduce the number of daily doses by prolonging the release of the product according to one dose if possible, two at most. Thus, to improve patient comfort and avoid, on the one hand, too many intakes during the day (risk of non-compliance with the dosage) and, on the other hand, reduce the risk of undesirable effects linked to blood peaks very high, efforts have been made, in accordance with the present invention, to keep the blood level at steady state at a minimum at 40 ng / ml, and with a maximum not exceeding 300 mg / ml. Such a result is not possible with the usual forms or of the immediate-action or delayed-action tablet type as marketed in Europe, in one or two doses per day, because they do not make it possible to stay within the rate limits. In addition, the microgranule form chosen allows better dispersion of the active ingredient. After the opening of the capsule, the microgranules spread widely in the digestive tract, resulting in an increase in the contact surface of the active ingredient - digestive liquids, and thus allow good distribution of the medicinal effect by better absorption. On the other hand, the fractionation of the dosage unit makes it impossible to create a high concentration of active substances at a point in the digestive tract, thereby reducing local intolerance and intra and inter patient variations.

Attempts are made to produce microgranules in the prior art containing Diltiazem. Thus, European patent application No. 0 149 920, filed in the name of ELAN CORPORATION plc, describes microgranules containing Diltiazem in combination with an organic acid and a lubricant in the outer membrane (according to American Pharmacopoeia No. 21 - " United States Pharmacopea No 21 ") which do not allow to obtain sufficient circulating blood levels and at least 40 ng / ml in one or two doses per day for daily doses between 100 and 500 mg, preferably 150 to 400 mg without the appearance of side effects harmful. In addition, the stability of such microgranules can be affected by the presence of organic acids which can influence the physicochemical characteristics of the outer or inner coating membranes of the microgranules.

• a) entre 5 et 35 % après une heure
• b) entre 15 et 40 % après deux heures
• c) entre 20 et 50 % après trois heures
• d) entre 30 et 75 % après quatre heures
• e) entre 40 et 80 % après six heures
• d) entre 55 et 95 % après huit heures.

The dosage form according to the invention is remarkable in that it consists of microgranules comprising Diltiazem in its center and an external membrane which allows a prolonged release of Diltiazem in an aqueous medium measured in accordance with the American pharmacopoeia USP No. 21 according to the following sequence:

• a) between 5 and 35% after one hour
• b) between 15 and 40% after two hours
• c) between 20 and 50% after three hours
• d) between 30 and 75% after four hours
• e) between 40 and 80% after six hours
• d) between 55 and 95% after eight hours.

The core will be from 0.2 to 0.5 mm in diameter and will be made up of neutral excipients, for example around 75% sucrose or fructose and 25% starch

In accordance with one of the variants of the process according to the invention, the neutral microgranules are introduced into a coating turbine and whose size is preferably between 0.2 and 2 mm.

A solution of PVP (polyvinylpyrrolidone) in water or a solubilizing organic solvent (for example ethyl alcohol, acetone) is prepared, and the microgranules are wetted with the PVP solution and an amount of active principle is sprayed until the granules On repeat the operation until the amount of active ingredient corresponding to the dosage has been used up.

Then, the microgranules are dried with hot air and / or by passage through a drying chamber. It is sieved and the humidity and the grain size are controlled.

According to the invention, several types of coating allow the external membrane to be produced. According to the invention, these coatings will be considered equivalent if they make it possible to obtain products which are bio-equivalent to those described below by way of nonlimiting example, the results of bio-availability being indicated below for the products. corresponding to these examples in order to allow those skilled in the art to appreciate said bio-equivalence.

In a first series of examples, a main constituent of the external membrane of the dosage form was used, a mixture of shellac and ethylcellulose.

In this case, an alcoholic solution of shellac and ethylcellulose and the appropriate amount of talc are prepared for coating.

The alcoholic solution of dewaxed shellac and ethylcellulose is applied and the talc is sprayed simultaneously. It is dried with hot air and sieved, the humidity and the grain size are controlled.

After acceptance of the product, following the controls provided during manufacture, the microgranules are put into capsules or the manufacture of tablets containing these microgranules.

The characteristics of the outer membrane of the microgranules thus obtained must make it possible to release Diltiazem in an aqueous medium according to the American method USP No. 21 in the following intervals:
10 to 20% after one hour
30 to 45% after four hours
60 to 75% after eight hours

For this, an alcoholic solution of dewaxed shellac and ethylcellulose was used, the respective proportions of which, expressed in dry weight, are 70 parts by weight of shellac for 30 parts by weight of ethylcellulose.

According to the embodiments of the microgranules whose outer layer contains shellac, the limits of each component used are shown in Table 1, expressed in proportion by weight relative to the total weight of finished product (microgranules in bulk). TABLE 1 COMPONENTS PROPORTION% Neutral granule 8-15 Diltiazem 60-85 Polyvinylpyrrolidone 4-6 Shellac 2-5 Ethylcellulose 1-3 Talc 0-10

For a better understanding of the invention, the limit curves corresponding to the case of the outer layer comprising shellac are indicated in FIG. 1 and the in vitro disintegration curves (American method USP No. 21). 2) as well as two examples of formulation, the first (curve n ° 3) which comprises 3.50% by dry weight of shellac and ethylcellulose and 6.95% by weight of talc and which is a formulation whose standards do not correspond to microgranules in accordance with the invention, and the second (curve no. 4) which comprises 4.75% shellac and ethylcellulose and 9.90% by weight of talc, the characteristics of which correspond to a formulation according to the present invention.

We have also included the results obtained in bioavailability using the formulation corresponding to the curve n ° 4 of figure 1. These results are reported in table II below for three dosages, per dose (180, 240, and 300 mg of Diltiazem per capsule) which are the three dosages retained as interesting after carrying out an effective dose interval study carried out by the applicant. These bioavailability studies in Table II were carried out on twenty-four volunteers in cross-study, and in repeated doses by comparing the product according to the invention (reference SR) compared to the commercial product marketed under the brand TILDIEM® of the company SYNTHELABO (60 mg tablet of Diltiazem). Except on days 1 and 7 of the study, patients received the equivalent of 180 mg to 240 mg per day for studies testing these dosages. In the study testing 300 mg SR, the dosage of the immediate reference product was 360 mg per day.

See table 2 Table caption Cmax observed: Maximum concentration Tmax observed: Time after which the Cmax is observed T 1/2: Elimination half-life time Cumulative AUC: Area under the curve showing the amount of Diltiazem absorbed in 24 hours the cumulative AUC is calculated by the trapezoid method AUC extrapolated: Area under the curve extrapolated to infinity TABLE 2 Product Protocol Cmax observed in ng / ml Tmax observed in hours T 1/2 in an hour Cumulative AUC in ng.h / ml AUC extrapolated ng.h / ml 180 mg SR Day 1 after single dose 99.4 5.7 7.45 1,298.5 1537.2 Day 7 (balance) after a single dose 125.5 4.7 7.3 1695.0 1746.3 60 mg reference Day 1 after three doses 61.5 16.5 31.1 977.5 2177.8 Day 7 (balance) after a single dose 100.0 2.3 6.5 850.7 886.0 240 mg SR Day 1 after single intake 141.2 5.9 7.9 1,811.3 2291.2 Day 7 (balance) after a single dose 178.1 4.95 6.5 2,424.95 2,529.8 60 mg reference Day 1 after 2 doses of 120 mg 103.4 7.4 16.4 387.7 1998.5 Day 7 (balance) after a single dose of 120 mg 172.2 2.7 5.7 1507.5 1582.8 300 mg SR Day 1 after single intake 142.4 7.1 10.0 1877.2 2507.7 Day 7 (balance) after a single dose 201.6 6.6 7.9 3090.2 3,176.1 60 mg reference Day 1 after a single 120 mg dose 77.7 4.2 5.3 687.3 754.6 Day 7 (balance) after a single dose of 120 mg 176.8 3.1 6.6 1843.7 1913.1

Furthermore, Figure 3 shows the plasma concentration of Diltiazem [C] expressed in nanograms per milliliter as a function of time [T] in hours on the first day (curve No. 1 for TILDIEM® and curve No. 2 for the product according to the invention), and FIG. 4 the same curve on the seventh day of administration for a dosage of 300 mg according to the invention in comparison with three times 120 mg in three doses of TILDIEM® for six days and once 120 mg on seventh day. Figures 5 and 6 show the comparison of a 180 mg dosage according to the invention in comparison with TILDIEM® 60 mg (administered three times from day 1 to day 6, then once on day 7), respectively on the first day and on the seventh day, while FIGS. 7 and 8 compare a 240 mg dosage according to the invention in comparison with 240 mg of TILDIEM® in two doses for six days, then 120 mg on the seventh day.

All of these results clearly show that with the dosage forms according to the invention, a circulating level of Diltiazem in the blood is always greater than 40 nanograms per milliliter and, therefore, these forms can be used in a single take. per day.

In a second series of examples, a mixture of Aquacoat® ECD 30 and Dibutylsebacate was used as the main constituent of the outer membrane. Aquacoat is an aqueous polymeric dispersion of ethylcellulose, marketed by the American company FMC, which contains 30% of solid components. Ethylcellulose represents 85% of solid components, the rest being made up of two stabilizers: sodium lauryl sulfate and cetyl alcohol.

In the formulations below, the plasticizer (for example dibutylsebacate) is used in an amount equal to 15 to 25% of the mass of Aquacoat expressed in dry weight. The characteristics of the external membrane of the microgranules thus obtained must allow to release Diltiazem in an aqueous medium according to the American method USP No. 21 at the following intervals:
15 to 35% after one hour
55 to 75% after four hours
75 to 95% after eight hours.

Using a 30% aqueous ethylcellulose suspension in proportions expressed as dry weight of 100 parts by weight and 25 parts by weight of dibutyl sebacate, the desirable limits of each component used are shown in Table 3, expressed below as proportion of dry weight relative to the total weight of finished product (bulk microgranules). TABLE 3 COMPONENTS PROPORTION% Neutral granules 8-15 Diltiazem 60-85 Polyvinylpyrrolidone 4-6 Aquacoat ECD 30 1-15 Dibutylsebacate 0.4-4 Talc 0-10

In the same way as with the shellac-based outer layer, the in vitro disintegration curves are indicated in FIG. 2 (American method USP No. 21) the limits corresponding to the intervals cited above (curves No. 1 and n ° 2), as well as three examples of talc-free formulation, the first (curve n ° 3) comprising 8% by dry weight of mixture Aquacoat® ECD 30 and Dibutylsébaçate (DBS), the second (curve n ° 4) comprising 8.8% of ECD 30 and DBS, and the third (curve n ° 5) comprising 9.8% of ECD 30 and DBS. Each of these curves is a little slower with each addition of excipient. A formulation containing 15% Aquacoat and DBS is too slow (curve n ° 6)

In order to clearly show the bio-equivalence of the formulations comprising the Aquacoat® and DBS mixture compared to those comprising the shellac and ethylcellulose mixture in their external membranes, the curves expressing the plasma concentration of Diltiazem are shown in FIG. 9 [ C] in nanograms per milliliter as a function of time [T] in hours during the administration of 300 mg of Diltiazem in microgranules according to the invention taken once on twenty-one volunteers, curve 1 relating to a formula comprising shellac and ethylcellulose conforming to curve 4 of FIG. 1, curve 2 relating to the formulation conforming to curve 5 of FIG. 2 and curve 3 relating to the formulation conforming to the curve 3 in Figure 2.

In FIG. 10, the mean curves of a study have been reproduced which have demonstrated the imbalance between a formula comprising shellac (curve n ° 1) conforming to curve 4 of FIG. 1 and an Aquacoat formula ( curve n ° 2) conforms to curve 6 of figure 2.

Finally, we have shown in FIG. 11 the results obtained during a single-use study on eighteen volunteers comparing 180 mg of the formulation in Table 3 (curve No. 1) in comparison with three times 60 mg of TILDIEM. ® (curve n ° 2)

All the results of these formulations are summarized in Table IV below. TABLE 4 Cmax observed in ng / ml Tmax observed in hours T 1/2 in an hour Cumulative AUC in ng.h / ml AUC extrapolated ng.h / ml 300 mg SR formulatin shellac 218.5 4.2 8.5 2,636.1 3,154.3 300 mg SR aquacoat formulation (curve 3 of figure 9) 275.5 3.0 7.2 2,792.8 3161.1 300 mg SR aquacoat formulation (Curve 2 in Figure 9) 201.5 5.6 7.4 2484.8 2,878.7 180 mg SR aquacoat formula 102.15 5.5 6.4 1160.1 1193.3 180 mg reference 176.95 3.75 5.7 1381.9 1397.7 Legend Cmax observed: Maximum concentration Tmax observed: Time after which the Cmax is observed T 1/2: Elimination half-life time Cumulative AUC: Area under the curve showing the amount of Diltiazem absorbed in 24 hours the cumulative AUC is calculated by the trapezoid method AUC extrapolated: Area under the curve extrapolated to infinity

The outer membrane of the products relating to Table 4 has the advantage of obtaining formulations whose release of Diltiazem is insensitive to pH.

Of course, equivalent results can be obtained by using other excipients such as the suspension of ETHOCEL AQ marketed by the company COLORCON, the EUDRAGIT® RL and RS or their equivalents sold by the company ROHM and HAAS, the equivalent formulas according to the invention to those described above being easily carried out by a person skilled in the art, these formulas should make it possible to obtain results bio-equivalent to one or the other of the above formulations.

All the dosage forms according to the invention make it possible to maintain a sufficient effective maximum blood concentration without excessive concentration peak so as to allow a dose per day whatever the indication treated (ie between 40 and 300 nanograms of Diltiazem per milliliter of blood taken), i.e. by varying the single daily dose to be absorbed by the patient. They therefore make it possible to obtain a decisive advantage in the administration of Diltiazem or of its pharmaceutically acceptable salts. The usual dosages can vary without inconvenience between 50 and 500 mg per day, in one or two doses. For two doses, a dose of 50 to 200 mg is preferred and for a dose of 120 to 400 mg depending on whether you are treating angina, hypertension or cerebral or peripheral circulatory failure.

The toxicity of the formulations compared to that of Diltiazem hydrochloride in powder form did not show any increase and on the contrary a decrease compared to the pure product Diltiazem.

Furthermore, the stability of the formulations has proved excellent, in particular for the formulations of the second group comprising Aquacoat®. For those containing shellac, we have found that it was essential to remove all traces of solvent at the end of manufacture. In all cases, it is advantageous to carry out heating to approximately 50 ° C. of the final mass of the microgranules before they are put into gelatin capsules, whether these have been prepared according to the conventional process in a turbine or by extrusion plus spheronization and coated turbine or using variants with fluidized air beds, for example of the GLATT, WURSTER type, well known to those skilled in the art, and which can allow direct use of the granulated active principle as an element of the microgranules.

Claims (16)

1. Pharmaceutical form for prolonged release of pharmaceutically acceptable Diltiazem comprising microgranules, of the type constituted in its center by a core filled with layers comprising the active principle, each microgranule comprising an external membrane, characterized in that the latter is suitable for release the Diltiazem applied to the neutral nucleus in an aqueous medium in the following proportions, measured according to the method of the American pharmacopoeia USP No. 21 a) between 5 and 35% after one hour b) between 15 and 40% after two hours c) between 20 and 50% after three hours d) between 30 and 75% after four hours e) between 40 and 80% after six hours d) between 55 and 95% after eight hours. 2. Dosage form according to claim 1, characterized in that the outer membrane is formed using an organic solution of the ethyl alcohol or acetone type, shellac and ethylcellulose in respective proportions of 70 parts by weight shellac and 30 parts by weight of ethylcellulose expressed in dry weight 3. Dosage form according to claim 2, characterized in that the proportions of Diltiazem released in an aqueous medium measured according to the American method USP No. 21 are substantially between.
10 to 20% after one hour
30 to 45% after four hours
60 to 75% after eight hours. 4. Dosage form according to claim 1, characterized in that the outer membrane consists of a plasticizer of the dibutylsébaçate type introduced into an aqueous suspension containing 30% ethylcellulose in respective proportions of 100 parts and weight of ethylcellulose and 15 to 25 parts by weight of plasticizer expressed in dry weight. 5. Galenic form according to claim 4, characterized in that the proportions of Diltiazem released in an aqueous medium measured according to the American method USP No. 21 are substantially between:
15 to 35% after one hour
55 to 75% after four hours
75 to 95% after eight hours. 6. Dosage form according to claim 1, characterized in that the external membrane of each microgranule comprises a proportion of talc less than 10% by total weight of microgranules. 7. dosage form according to claim 1, characterized in that it comprises, expressed in total weight of microgranules, 8 to 15% by weight of neutral core, layers of Diltiazem, in an amount of 60 to 85% by weight mixed with of polyvinylpyrrolidone in an amount of 8 to 15% by weight, 0.1 to 10% by weight of talc and 1 to 20% by weight of outer membrane. 8. Dosage form according to claim 7, characterized in that the outer membrane comprises, expressed in total weight of microgranules, from 2 to 5% shellac and from 1 to 3% of ethylcellulose. 9. Dosage form according to claim 7, characterized in that the outer membrane comprises, expressed in total weight of microgranules, from 1 to 15% by weight of ethylcellulose and from 0.1 to 4% by weight of plasticizer. 10. A method of obtaining the dosage form according to claim 1, according to which a conventional neutral core is used whose size is between 0.2 and 2 mm, layers of Diltiazem and / or its pharmaceutically salts are applied. acceptable, characterized in that this application is carried out using a solution of polyvinylpyrrolidone in water or a solvent with which microgranules are previously wetted, then the active pincipe is sprayed and mixed with said solution until total depletion of the quantity corresponding to the desired title, said microgranules being dried until total evaporation of the solvent. 11. The method of claim 10, characterized in that, to form an outer coating layer, an organic solution of shellac and ethylcellulose and an appropriate amount of talc is prepared, then the organic solution of shellac is applied and ethylcellulose and the talc is sprayed simultaneously and dried with hot air until the solvent has evaporated. 12 Method according to claim 10, characterized in that, to form the outer coating layer, a suspension of Aquacoat® and of plasticizer and an appropriate amount of talc is prepared, then the suspension of Aquacoat® and plasticizer and the talc is sprayed simultaneously and dried with hot air until the solvents have completely evaporated. 13. Medicament according to claim 1, characterized in that it comprises the microgranules included in a unitary presentation of the capsule-bag or tablet type, dosed between 50 and 250 mg of Diltiazem and intended to be absorbed twice a day for the treatment of angina, hypertension or cerebral and peripheral circulatory insufficiency. 14. Medicament according to claim 1, characterized in that it comprises the microgranules included in a unitary presentation of the capsule type - sachet or tablet - dosed between 100 and 500 mg of Diltiazem and intended to be absorbed once a day for treatment angina, hypertension, or cerebral and peripheral circulatory failure. 15. The medicament according to claim 14, characterized in that it comprises the microgranules included in a unitary presentation of the capsule type - sachet or tablet - dosed with 300 mg of Diltiazem and intended to be absorbed once a day for the treatment of 'hypertension. 16. Medicament according to one of claims 13 or 14, characterized in that the circulating blood levels obtained at equilibrium for a day are between substantially 40 and 300 nanograms per milliliter of blood collected.

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